Method of separating dust from gases.



H. HOWARD. METHOD 0F SBPABATING nUsT PROM GASES.

APPLICATION I'ILED 5111.29, 100D. Q'/, Patented Sept. 13,1910.

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,UNITED STATES PATENT oEEIoE.

HNRY HOWARD, OF BOSTON, MASSACHUSETTS.

METHOD OF SEPARATING DUST FROM GASES.

-Application led January 29, 1909. Serial No. 474,958.

To all whom it may concern:

Be it -known that I,1HENRY HOWARD, a citizen of theUnited States, .residing at Boston, in the county of Suffolk and State of Massachusetts, have invented certain new and useful Improvements in Methods of Separating Dust from Gases, of which the following is a specification. This invention relates to t-he separation-of dust or fume from, dust-laden gases,and articularlyfrom the hot ases escaping rom roasting'or smeltingv urnaces.. For the separation of dust from such gases it is usual to rovide `large settling chambers, often fitted with internal bailles or the like for directing the ases ina'4 tortuous path through the cham er: such chamberslare however quite inefficient asl applied to the separation of impalpable fume suspended in the gases escaping from metallurgical furnaces. It has also been proposed to pro- .vide in a settling chamber of this character la series of superposed horizontal or inclined shelves, relatively widely separated, for the purpose of shortening the paths ofthe fall'- ing dust particles and therefore permitting.

amore nearly complete subsidence of the dust in a given length o'f passage, this construction bein equivalent 1n effect to widening the cham r with a proportionate reduction of its height. It has heretofore been` assumed that the function of such shelves was solely to lessen the path of the falling particles to their points of deposit, and in constructions heretofore proposed wherein the spaces between the shelves constitute in fact dust-chambers of .considerable height,-

- these shelves appear to possess this function y only. I have ound however that when the stream of dust-laden gas is confined in close proximity to a dust-retaining surface, as by the provision of metallic shelves separated I 1' by a 'vertical distance of two to three inches or even much less, and so positioned that the dust will not slide upon them, a wholly novel and su rising result is secured, in

that the cham er acquires practically the,

' character of a filter, retainin the finest dust articles., The etiiciency of t e separation is increasediaut of all proprotion to the reduction infvertical distance between the several shelvesyand when it-is considered that this increase in eliieiency is due tothe retention of the finer suspended particles, it is clear that a radical chan e has occurred in the inode of operation o the apparatus. While 'l all of the phenomena to which this'incrcased efficiency may be due have not been determined it is believedeto result chiefly from theretardation by the dust-bed lying upon the shelves, of the lower portion of the shallow 'confined stream of dust-laden gas,tliis ylower portion in case of closely-spaced shelves comprising a substantial proportion of the whole stream. Thedust particles in this'retardeddportion of the stream rapidly settle out, an in the course of the passage throughthe apparatus the particles in the in orerapidly moving portions of the stream are carried intoandtrapped or held by the slowly moving portion of the stream, this result, being robably aided by eddy currents setup tween adjacent portions of Specification of Letters Patent. Patented Sept. 13, 1910.

the gas stream moving at different velocities. It is furtherobserved in practice that the linlet end of theshelves quickly becomesl 'obstructed and nearly closed by an accumulated de osit of dust, which slowly extends rearwar ly or toward tho outlet' end of the shelves. It is quite probable that Athe obstructive deposit at the inlet end, by` reason of the eddy currents set up in the gases passing it, serves to increase the etlicieney of the operation. At suitable intervals, de pending upon the dust-content of the gases, the de osit is removed from 4the shelves,

either y a steam or air blast, or by a suitable nozzle, adapted for insertion 'between the shelves and connected to a vacuum pum y.

or suitable aspirator, appropriate dust-co lecting devices being provided, or the dust4 may be removed by a scraper. L

The'method may be carried into effect 1n widely varying forms of apparatus, it beino' essential merely that the stream of dust' la en gas be confined ordirected at low ve- 'locity in close proximity to a dust retaining surface. Where a large capacity is reiiired, as is usually the case, a series of such (dust-retaining surfaces will be provided, preferably in the form of superposed, closely spaced shelves. paratus may be constructed in the general manner described in my prior'v Patent No. 896,111, the shelves bein preferably spaced at distances not excee ing two to three inches in the clear.-

Referring to the accompanying drawings, which illustrate a specific apparatus for removing dust from the sulfurous gases produced in pyritcs burners,-Figure 1 is a longitudinal' vertical section on the liiieI-I In this case the api of Fig. 2; Fig. 2 is a transverse vertical sectionfon the line II--II' of Figfl; and Fig.

vertical upper en of the supply 'A ,'vf'alved inletsb ofthe two chambers 1 is a horizontal passage 7 to which the gases are l supplied'by pipe 8. At the lower end of the `verticalpassage4 is an outlet 9 which ieliversthe gases into an uptakelO having an outletll controlled' by a'valve 12. Ahori' i zontal passage 13 having a delivery pipe 14 extends over the outlets 11 of bothy cham bers. The outer wall of each chamber, at its "receiving-end, is providedrwithv avertical; series Iof removable tiles 15. Lateral` cleaning-openings 16, with doors, are pro? vided at the lower ends ofthe passages 4:, 10.

In operation, the AValves 6, l2 are opened and vgases suppliedthrough the pipe 8 passinto the horizontalv chamber 7." and thence 'i .I through the openings 5 into the vertical supply-.pass-ages 3.v The entering gases then subdivide 'and pass between the shelves, whereon the dust is deposited. The gases leaving'tlieshelves enter the discharge-passages 4 and escape through the openlngs 9, uptake's 10, openings 11,- hori- 4zontal passages 13 and pipe 14.V The c ol- ,tion -it 'is n'ece'ssa lected'dust may be removed frpiil the shelves .of either chamber without interrupting ,the iow ofgases by closing its valves 6*,l 12, re moving the tiles 15, forcing 4the dust from the-shelves into-thepassage 4 and removing it at the bottom through theopenings 16.

In orderfto insure high efficiency of operathat theinflo`wing gas should .be distributed with substantialmuni-1 u forrnity through the several interspaces, -5o

culties inthe case of yj'gasesat su-per-atmos,4

'fand' this distribution presents special ditli- Apheric temperaturesf'as 'those' from metallurgical furnaces. Thus, if heated "dusti laden gases be introduced into the'central or lowerportion of la chamber subdivided by horizontal shelves and permitted to escape from the upper ortionthereof at the'opposite end', it will e found that instead'of increasin@ the eiiicienc of se aration the 'shelvesmay actually decrease it, for the rea-v son that the heated gases Will tend" tov iow at vincreased velocity through a few Yinter- A'spaces in the upper portion of the chamber,

without aifording .suiiicient timefor vsettlingr In'the articular form of apparatus illustrated in Jigs. 1 and 2, the necessary uniformity `of flow is secured by providing gas-passages extending transversely ofthe shelves at opposite .ends of'thechamber, in-

troducing the heated gas into the upper portion of the chamber at, one end, and Withdrawing the'purified and somewhat cooler', gas from the lower portion of the passage at the outlet end. This affords an automatic regulation of the flow through the several interspaces, because if the 'gases tendl to flow too rapidly through the upper interspaces, thev'ertical column of gas in the discharge 4passage acquires a relatively higher temperature and -lower'specific gravity, and

thereupon exerts a back pressure and retards' the-movement of gases between the upper shelves. a"It is clear howeverfthat substantial uniformity of fiowbetween the'shelves maybelothervvise'obtained, asv for eXample by apartialclosure or revulation of the-orltices at thef-inlet ends o1 the several interspaces' by means of any suitable form of damper or valve, as that lllustrated at 17m i"ig. yI do not' desire therefore tobe `restricted to the use of any particular apparatus incarrying my methodjinto ei'ect.

I claim :4-

The method of separat-ing dukst from gases,

,which consists 1n passingdust-laden gases at'law velocity through interspaces' between parallel dust-retaining surfaces, regulating the passage of the gases to secure substantial uniformity of flow between the surfaces, andconning the gases in close proximity to said surfaces.

In testimony whereof I atlix nay-signaturein presence of two witnesses. y

y HENRYy HOI/VARI).

iVitnesses:

ALBERT CHAMPION GILBERT,A Osonnn BazANsoN. `v 

